Road maintenance method and vehicle

ABSTRACT

The cutting blades and smoothing blades of a road maintenance vehicle are adjustable in position with respect to the wheels to avoid extremes in changes in the depth of a cut by a blade or the height of the blades caused by wheels of the vehicle dropping into low places in a road. By including a selected number of wheels mounted to the same stiff frame, the wheels riding on the highest part of the road will lift the rigid frame and other wheels rather than the wheels riding on the lowest part of the road determining the depth of the cut of the cutting blades. The height of the blades with respect to the wheels can then be adjusted so that they never cut too deep and overly stress the blades but do cut the highest elevations of the road and move the loose dirt and gravel into the lower parts of the road. A first frame is supported by wheels and a second frame is movably mounted to the first frame.

RELATED CASES

This application is a continuation of U.S. provisional patentapplication 61/187,596 filed Jun. 16, 2009, by inventor, Lee M. Waldo.The benefit of provisional patent application 61/187,596 is claimed.

BACKGROUND OF THE INVENTION

This invention relates to road maintenance and more particularly tomethods and equipment for smoothing the surface of roads.

One type of road maintenance equipment for smoothing the surface ofroads includes a vehicle that is pulled by a tractor or truck andincludes one or more cutting or shearing or buster blades that breakelevated portions of the road into loose gravel and dirt and one or morestriker or smoothing blades to spread the loose gravel and dirt over theroad. One prior art road maintainer of this type has a centrally locatedV-shaped cutting or shearing blade and two side cutting blades that cutthe road material and deliver it to a centrally located striker orsmoothing blade that spreads the material across the road. This priorart road maintainer is disclosed in U.S. Pat. No. 5,071,284.

This prior art road maintainer has several disadvantages, such as forexample: (1) the resistance to cutting is at times undesirable inmagnitude; (2) the height of the cutting and smoothing blades above theroad is controlled by only two wheels near the end of the roadmaintainer and thus subject to wide variations as wheels alternatelycontact the lowest parts of the road and the highest parts of the road;(3) the scrapped and cut material is not distributed with sufficientevenness over the road; and (4) the height of the cutting and smoothingblades is not easily adjustable.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to provide a novel methodand apparatus for maintaining roads.

It is a further object of the invention to provide a novel method andapparatus for controlling the magnitude of stress on the blades of aroad maintenance vehicle.

It is a still further object of the invention to reduce the variationsin the elevation of the blades of the maintenance apparatus during theroad surface smoothing operation.

It is a still further object of the invention to control the height ofthe blades above the road by any of a plurality of different wheels onthe road.

It is a still further object of the invention to provide a method andapparatus for cutting free material from high spots on a road anddistributing it evenly.

It is a still further object of the invention to provide a method andapparatus for distributing the cut or scrapped material from a road overa wider area of the road.

It is a still further object of the invention to provide a method andapparatus by which the operator of road maintenance equipment can adjustthe height of the blades.

In accordance with the above and further objects of the invention, aroad maintenance vehicle is constructed to be towed by a tractor or atruck to smooth the surface of a road. For this purpose, a plurality ofblades with selected length and angle are provided to cut into or burstor scrape the high points on the surface of the road and move thecuttings or scrapings through a plurality of paths towards the rear ofthe vehicle. The vehicle includes an angular blade designed to receivethe cuttings or scrapings from a number of paths and channel some of itto the center of the road for the proper crown while filling in lowspots by material being moved towards the rear most blade.

The vehicle has a plurality of wheels so that as it is towed, the heightof the blades is controlled by the wheel that is riding over the highestpoint rather than by the wheel that is in the lowest depression to causethe blades to follow the road more evenly. The height of the blades withrespect to the wheels can be adjusted by any suitable mechanism such ashydraulic cylinders under the control of an operator prior to a levelingoperation and can be locked in place.

From the above description it can be understood that the roadmaintenance vehicle and method of this invention has several advantagessuch as: (1) the stress imposed on cutting blades is kept withinmanageable limits by controlling the angle of the blade and the depth ofthe cut for specific length blades and using multiple blades; (2) thedepth of cuts is maintained reasonable in spite of low portions in theroad that cause the wheels to drop to a low depth by including asufficient number of wheels so that the height of the cutting blades iscontrolled by the wheel riding on a relatively high portion of the road;(3) a plurality of cutting blades is used to distribute the loosed roadmaterial more evenly; and (4) the height of the cutting and smoothingblades can be easily adjusted.

BRIEF DESCRIPTION OF THE DRAWINGS

An above noted feature of the invention will be better understood fromthe following detailed description when considered in connection withthe following drawings, in which:

FIG. 1 is a flow diagram of a process for maintaining road surfaces;

FIG. 2 is a fragmentary simplified side view of a truck pulling a roadmaintenance device in accordance with an embodiment of the invention;

FIG. 3 is a simplified partly schematic plan view of a tractor or othervehicle pulling a road maintenance vehicle in accordance with anembodiment of the invention;

FIG. 4 is a perspective view of a road maintenance vehicle in accordancewith an embodiment of the invention; and

FIG. 5 is a perspective view from another direction of the roadmaintenance vehicle of FIG. 4.

DETAILED DESCRIPTION

In FIG. 1 there is shown a flow diagram 10 of a process for using theroad maintenance vehicle of this invention comprising the step 12 ofdetermining relevant road surface condition, the step 14 of adjustingthe cutting and smoothing blades, the step 16 of pulling the roadmaintenance vehicle at a fast relevant surface speed for the relevantroad surface conditions and the tep 18 of pulling the road maintenancevehicle at a slow relevant speed. The step 14 of adjusting the bladesfor the relevant road surface conditions includes the step 24 ofadjusting the height of the cutting blades within the blade-heightwheel-averaging arrangement to keep the stress on the cutting bladeswithin tolerances, the step 26 of adjusting the height of the smoothingblade to build a crown and smooth out ruts and holes, and the step 28 ofadjusting the angle of the cutting blades to correspond to the length ofthe blades, road surface conditions, number of blades and height of theblades with respect to the wheels of the vehicle to form a crown.

In this specification, the term “blade-height wheel-averagingarrangement” means the selection and positioning of the wheels of theroad maintenance vehicle to avoid extremes in changes in the depth of acut by a blade or the height of the blades caused by wheels of thevehicle dropping into low places in a road. By including a selectednumber of wheels mounted to the same stiff frame, the wheels riding onthe highest part of the road will lift the rigid frame and other wheelsrather than the wheels riding on the lowest part of the road determiningthe depth of the cut of the cutting blades. The height of the bladeswith respect to the wheels can then be adjusted so that they never cuttoo deep and overly stress the blades but do cut the highest elevationsof the road and move the loose dirt and gravel into the lower parts ofthe road. The term “cutting blade” in this specification includesscarring blades or bursting blades or any blades constructed and locatedto break up hardened material on the road such as raised gravel or dirtmounds into loose material that can be moved into lower spots. The term“smoothing blade” shall mean a blade that moves and distributes loosematerial to fill in ruts and build a crown on the road.

The cutting blades are arranged in a cutting-blade distributionarrangement. In this specification, the words “cutting-bladedistribution arrangement” means an arrangement of a plurality of cuttingblades to avoid excessive stress on any one blade while cutting andspreading the cut dirt and gravel over the entire path of themaintenance vehicle with an effective evenness. In this specification,the term “effective evenness” means the distribution of loose dirt andgravel in a manner that provides material to fill in holes anddepressions evenly rather than having more loose material than neededalong one line in the road such as the center of the road as in the casewith cutting plates that have a central opening with V-shaped bladeportions extending outwardly and forwardly to channel material to thecenter of the road or V-shaped blade portions with a point facingforwardly to move loose dirt and gravel to the sides. In thisspecification, the word “forwardly” means the direction that the roadmaintenance vehicle is being pulled.

The speed at which the road maintenance vehicle is pulled depends on therelevant road surface conditions. In this specification the terms“relevant road surface condition” includes considerations such as howmuch moisture is in the road or how dry the road is, sometimes referredto as soft or stiff road surfaces and the size of any ruts and holes, ifany. The words “slow relevant road surfaces” means the relevant roadconditions are considered slow relevant road conditions when the roadsurface is dry and stiff and/or the ruts and holes are deep, such asmore than three inches deep. Under slow relevant road conditions, themaintenance vehicle is pulled at a speed of between 10 and 15 mph withan average speed less than 15 mph. This speed is referred to in thisspecification as “slow relative speed”. On the other hand, “fastrelevant road surface conditions” means the surface conditions thatexist when the road surface is moist and soft and the ruts and holes areshallow such as no more than 2 or 3 inches. The road maintenance vehiclecan be pulled at speeds up to 20 mph and average over 15 mph under fastrelevant road surface conditions. This speed is sometimes referred toherein as “fast relative speed”.

In FIG. 2, there is shown a fragmentary schematic side view of a roadmaintenance operation 30 being performed by a truck or other heavyvehicle 32 driven by an operator 34 pulling a road maintenance vehicle36 in accordance with the invention. The heavy vehicle 32 will pull theroad maintenance vehicle 36 at a speed in accordance with the relevantroad surface conditions. In this specification, the term “relevant roadsurface conditions” shall mean how much moisture is in the road or howdry the road is, sometimes referred to as soft or stiff road surfacesand the size of ruts and holes if any. The road maintenance vehicle 36includes a plurality of wheels, three of which are shown at 38A, 38B and38C in FIG. 2 on one side of the road maintenance vehicle. Othercorresponding wheels are shown on the other side.

The number of wheels is chosen in accordance with typical roadconditions for which the vehicle is designed. It is intended to preventa blade from dropping low because a wheel is in a low spot to put toomuch stress on the blade and damage it or cause excessive wear or anexcessively deep cut. Instead, there are sufficient wheels so that oneof them will always be on a high spot. The frame of the vehicle 36 towhich the wheels are mounted is stiff so that the highest wheel willdetermine the elevation of the vehicle. As will be describedhereinafter, the blades are adjustable with respect to the wheels sothat the blade height may also be adjusted in accordance with therelevant road surface conditions.

In FIG. 3, there is shown a simplified plan view of the road maintenanceequipment of FIG. 2 in operation showing the vehicle 32, which may be atruck or tractor, pulling the road maintenance vehicle 36. As shown inthis view, the road maintenance vehicle 36 includes a hitch 42, a maincarriage or frame 44, and a movable blade carriage or frame 46. The maincarriage 44 has mounted to it the axles for the wheels 38A-38C and40A-40C so that it rises and falls in accordance with the wheels 38A-38Cand 40A-40C as the road maintenance vehicle 36 is pulled down the road.To form a complete blade-height wheel-averaging arrangement, however,the movable blade frame 46 must be mounted and controlled by a hydrauliccylinder 48 (FIG. 4) under the control of the operator 34 (FIG. 2) toposition the movable blade frame 46 with respect to the rigid main frame44 at a proper elevation for the cutting blades 50A-50D and thus toavoid undue stress.

The width of the blade-height wheel-averaging arrangement is normallyapproximately 8 feet and is intended to cover a lane of a road. Thecutting blades 50A-50D are adjustable in angle to move loose gravel anddirt to their out edges. Thus, the blades 50A and 50B as the vehicle isbeing pulled, move material to the outside or the edge of the roadwayand the blades 50C and 50D are angled to move material towards thecenter of the roadway or the outside of the lane. A smoothing blade 52is also positionable to form an angle and move the loose material to thecenter or crown of the road. The movable blade carriage 46 itself isadjustable in position by the hydraulic cylinder 48 to position all ofthe blades and complete the blade-height, wheel-averaging arrangementsfor smoothing out of the road.

In FIG. 4, there is shown a fragmentary perspective view of themaintenance vehicle 34 more clearly showing the hydraulic cylinder 48and movable blade frame 46 connected by hydraulic lines 54. As moreclearly shown in this view, the movable frame 46 may move up and down toposition the blades appropriately. In FIG. 5, there is shown anotherperspective view of the road maintenance vehicle 36 showing the cuttingblade 50D mounted to the movable frame 46 (FIGS. 3 and 4) by a support56D attached to it and attached to the movable frame 46 so that itsangle may be changed by movement with respect to the movable frame 46and thus change the angle of the cutting blade 50D. Similarly, thesmoothing blade 52 (FIG. 3) is supported and its angle may be changed.

From the above description, it can be understood that, the roadmaintenance vehicle of this invention has several advantages, such as:(1) the stress imposed on cutting blades is kept within manageablelimits by controlling the angle of the blade and the depth of the cutfor specific length blades and using multiple blades; (2) the depth ofcuts is maintained reasonable in spite of low portions in the road thatcause the wheels to drop to a low depth by including a sufficient numberof wheels so that the height of the cutting blades is controlled by thewheel riding on a relatively high portion of the road; (3) a pluralityof cutting blades is used to distribute the loosed road material moreevenly; and (4) the height of the cutting and smoothing blades can beeasily adjusted.

While a preferred embodiment of the invention has been described in somedetail, it is to be understood that within the scope of the appendedclaims, many modifications and variations of the invention are possible.Accordingly, it is to be understood that, within the scope of theappended claims, the invention may be practiced other than asspecifically described.

1. A road maintenance vehicle, comprising: a first frame supported by aplurality of wheels; a second frame movably mounted to said first frame,whereby the second frame may be adjusted with respect to said pluralityof wheels; a plurality of cutting blades; at least one smoothing blade;said plurality of cutting blades and said at least one smoothing bladebeing mounted to said second frame whereby said plurality of cuttingblades and said at least one smoothing blade may be adjusted in positionwith respect to said plurality of wheels; said first frame, said secondframe, said plurality of cutting blades, said at least one smoothingblade and said plurality of wheels being arranged in a blade-heightwheel-averaging arrangement.
 2. A road maintenance vehicle in accordancewith claim 1 wherein the plurality of cutting blades are moveablyconnected to the second frame wherein they may be adjusted to acutting-blade distribution arrangement.
 3. A method of maintaining aroad with a road maintenance vehicle that includes a first framesupported by wheels, a second frame movably mounted to the first frameand movably supporting blades, comprising the steps of: determiningrelevant road surface condition; adjusting the movably supportingblades, said first frame and said second frame into a blade-heightwheel-averaging arrangement; and pulling the road maintenance vehiclealong the road at a fast relevant speed and a slow relevant speed inaccordance with the relevant road surface condition.